Energy storage technology has received significant attention for portable electronic devices, electric vehicle propulsion, bulk electricity storage at power stations, and load leveling of renewable sources, such as solar energy and wind power. Lithium ion batteries have dominated most of the first two applications. For the last two cases, however, moving beyond lithium batteries to the element that lies below-sodium-is a sensible step that offers sustainability and cost-effectiveness. This requires an evaluation of the science underpinning these devices, including the discovery of new materials, their electrochemistry, and an increased understanding of ion mobility based on computational methods. The Review considers some of the current scientific issues underpinning sodium ion batteries.

The emerging chemistry of sodium ion batteries for electrochemical energy storage.

Positive electrodes for Li-ion and lithium batteries (also termed “cathodes”) have been under intense scrutiny since the advent of the Li-ion cell in 1991. This is especially true in the past decade. Early on, carbonaceous materials dominated the negative electrode and hence most of the possible improvements in the cell were anticipated at the positive terminal; on the other hand, major developments in negative electrode materials made in the last portion of the decade with the introduction of nanocomposite Sn/C/Co alloys and Si−C composites have demanded higher capacity positive electrodes to match. Much of this was driven by the consumer market for small portable electronic devices. More recently, there has been a growing interest in developing Li−sulfur and Li−air batteries that have the potential for vastly increased capacity and energy density, which is needed to power large-scale systems. These require even more complex assemblies at the positive electrode in order to achieve good properties. This r...

Positive Electrode Materials for Li-Ion and Li-Batteries†

Owing to almost unmatched volumetric energy density, Li-ion batteries have dominated the portable electronics industry and solid state electrochemical literature for the past 20 years. Not only will that continue, but they are also now powering plug-in hybrid electric vehicles and electric vehicles. In light of possible concerns over rising lithium costs in the future, Na and Na-ion batteries have re-emerged as candidates for medium and large-scale stationary energy storage, especially as a result of heightened interest in renewable energy sources that provide intermittent power which needs to be load-levelled. The sodium-ion battery field presents many solid state materials design challenges, and rising to that call in the past couple of years, several reports of new sodium-ion technologies and electrode materials have surfaced. These range from high-temperature air electrodes to new layered oxides, polyanion-based materials, carbons and other insertion materials for sodium-ion batteries, many of which hold promise for future sodium-based energy storage applications. In this article, the challenges of current high-temperature sodium technologies including Na-S and Na-NiCl2 and new molten sodium technology, Na-O2 are summarized. Recent advancements in positive and negative electrode materials suitable for Na-ion and hybrid Na/Li-ion cells are reviewed, along with the prospects for future developments.

Sodium and sodium-ion energy storage batteries

As compared to bulk materials, magnetic nanoparticles possess distinct magnetic properties and attempts have been made to exploit their beneficial properties for technical and biomedical applications, e.g. for magnetic fluids, high-density magnetic recording, or biomedical diagnosis and therapy. Early magnetic fluids (MFs) were produced by grinding magnetite with heptane or long chain hydrocarbon and a grinding agent, e.g. oleic acid [152]. Later procedures for MFs precipitated Fe 3+/Fe 2+ of an aqueous solution with a base, coated the particles by oleic acid, and dispersed them in carrier liquid [161]. However, besides the elemental composition and crystal structure of the applied magnetic particles, particle size and particle size distribution determine the properties of the resulting MF. Many methods for nanoparticle synthesis including the preparation of metallic magnetic particles have been described in the literature. However, there still remain important questions, e.g. concerning control of particle size, shape, and monodispersity as well as their stability towards oxidation. Moreover, peptization by suitable surfactants or polymers into stable MFs is an important issue since each application in engineering or biomedicine needs special MFs with properties adjusted to the requirements of the system.

Synthesis and Characterization

Inorganic Solid Fluorides: Chemistry and Physics

When La 2 CuO 4 is treated with pure F 2 gas at 200°C, the X-ray diffraction pattern of the resulting product is characteristic of a new single phase derived from the K 2 NiF 4 -type structure. An enhancement of the orthorhombic distortion relative to the starting oxide is observed with: a = 5.342 A; b = 5.436 A and c = 13.192 A. Both weight uptake and increase of the c unit cell constant could be consistent with an incorporation of fluorine atoms in the lattice. This new compound is superconducting at T c = 40 K with H c1 ⋍ 700 Oe and exhibits a strong diamagnetic susceptibility ( χ g = -6.13 × 10 -3 emu / g ) at 6 K under an applied field of 1 Oe

Stabilization of a new superconducting phase by low temperature fluorination of La2CuO4

EPR experiments have been performed on glasses related to the CaF2BaF2AlF3 system. Fluctuations of the EPR parameters are observed in the case of divalent ions which occupy distorted sites. The trivalent ions occupy sites of “fully rhombic” symmetry. A comparison with the EPR parameters obtained for crystallized α-CaAlF5 leads to the conclusion that the glass is built up by random type chains containing aluminium separated in various ways by the divalent cations, the coordination numbers of which may differ.

Jean-Michel Dance

Papers

Inorganic Solid Fluorides: Chemistry and Physics

Stabilization of a new superconducting phase by low temperature fluorination of La2CuO4

EPR of transition metal ions (Mn2+, Cu2+, Cr3+, Fe3+) in fluoroaluminate glasses

The Nasicon-like copper(II) zirconium phosphate Cu0.5Zr2(PO4)3 and related compounds

Die Verfeinerung der Weberitstruktur der Verbindung Na2NiFeF7